Meanwhile, for the shipped chocolate filling, in a double boiler or a microwave set on low power, heat the 6 ounces chocolate chip with 1/2 cup of the cream until the chocolate is just melted, stirring often. Let cool to room temperature. In a chilled bowl, beat the remaining 1 cup cream until thick. Add the chocolate mixture and the vanilla and beat until soft peaks form. Spread the whipped chocolate mixture over the truffle filling in the crust. Refrigerate overnight.